Floating Bodies

Hi

I'm working on my Master Thesis about Internal Erosion in granular media composed of spherical particles. I want to simulate a 3D upward flow through a granular specimen.
I generated about 230 speherical particles and I have assigned them the function "floating". I tried before defining rhopbody and then relative weight but at the end
of each simulation the particles still didn't move.
When i tried defining "massbody" , the simulation interrupted with this comment:

'particle boundary out - type: Floating cause: Speed p:22 id:78251 pos:(0.349773, 0.070138, 0.139592)'
...

Text: A boundary particle was excluded.

I can't understand why deining "massbody" gave me this error meanwhile with rhopbody or relativeweight the simulation goes untill the end but with the particles not moving.

My "floating" definitcion is the following:

MASSBODY:
floatings
floating mkbound="1-238" property="sand"
massbody value="1700" /
/floating
/floatings

properties
propertyfile file="Floating_Materials.xml" path="materials" /
/properties



I hope I've made myself clear.

Thank you in advance

Best Regards

Gabriele Quarzicci

Comments

  • Most of my problems with floating objects are caused by the objects not being filled with floating particles. Assuming that you are using the gencase "drawsphere" to make your granular media (as opposed to importing STL files, etc.), are you setting (setdrawmode mode="full" ) before creating the spheres? If not, the sand grains might be hollow, which could cause problems.

    One easy way to check to see if they are hollow or not is by loading the CaseYourcase_bound.vtk file in ParaView. You can visualize particles by "mk" for clarity, and if it's hard to tell if a sand grain is full or not, you can use the "Clip" filter in ParaView to cut the sand grains in half (Google this if you're unsure how to use filters in ParaView). If they are indeed full of particles, then at least you can rule this problem out.

    For what it's worth, I've had the easiest time using "rhopbody" to govern the floating behavior of my floating objects. Since you are using "Floating_Materials.xml," be sure to add in a "sand" entry to that file with the proper physical properties.
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